Evolution, Energetics, and the Vicious Circle
The downside of being too smart for our own good
Before we move on, I wanted to mention a couple of stories that came out around the new year that deal directly with some of the themes we explored in the Hunter-Gatherers and Health series of posts.
We learned about the basics of metabolism, that is, how living organisms acquire energy from their environment. As Herman Pontzer puts it, evolution is all about converting energy into offspring. The takeaway is that humans require many more daily calories to power our metabolic engine (including our large brains) than our closest primate relatives, and we evolved to expend a lot more energy to get those calories in the form of physical exercise. We also learned that our energy expenditure is not fixed as is often naively portrayed, but varies based on the amount of calories we take in. We also saw that existing narratives for obesity (“calories in-calories out”) and advice ("eat less, move more") have been inadequate to explain or solve the problem.
This article by Arianne Shahvisi provides a good explanation of how the acquisition of energy allows living things like us to overcome the laws of thermodynamics, if only for a little while:
Food can fuel bodily order because it is a low-entropy source of energy, meaning it provides a budget—both energetic and entropic—for bodily processes. It owes this property to nuclear fusion reactions in the core of the sun, which maintains a temperature imbalance with respect to the earth that allows it to supply the planet with a stream of high-energy, low-entropy photons. These photons are incident on plants, algae and cyanobacteria, whose cells synthesise the basic units of organic matter on which the rest of the food chain depends. We are all solar-powered (or nuclear-powered, if you prefer), and, crucially, stars persist long enough to provide not only the entropy gradients needed for life, but the timescales required for the evolution of interesting versions of it.
Life is energetically expensive. Even if you lie completely still, the cost of living is around 1500 kilocalories per day – the amount of energy it would take to heat eighty litres of water from tap temperature to that of a scalding bath. Most is spent on homeostasis, the processes by which our bodies stay more or less exactly as they are. Homeostasis is sometimes used as a way of defining life itself: living beings can maintain steady internal states despite changeable external conditions. One of the earliest formulations was physiologist Claude Bernard’s description, in the 1850s, of a ‘milieu intérieur’: ‘All of the vital mechanisms, however varied they may be, have always one goal, to maintain the uniformity of the conditions of life in the internal environment ... The stability of the internal environment is the condition for the free and independent life.’
What It Costs to Live (London Review of Books)
The first study looked at how humans use energy. One of the study's authors was Herman Pontzer, the author of Burn. Another was Michael Gurven, an anthropologist who was the co-author of the definitive paper that debunked the myths surrounding the average lifespan of hunter-gatherers. The researchers looked at groups we've seen before such as the Hadza and the Tsimané.
There are fundamentally two ways to increase the amount of energy available to you and they are basically the same for organisms as they are for entire countries. One is to increase your energy efficiency. The other is to increase the overall amount of energy you take in. This can be done, for example, by acquiring energy at a faster rate per unit of labor.
To put it into terms of energy return on energy invested (EROI), you can either decrease the investment while keeping the returns the same (become more efficient), or increase your investment, but gain larger net returns as a result (increase the amount of energy you take in). A negative return, of course, is not sustainable in the long term.
An example is warm-blooded animals. Warm-blooded animals have to burn a lot more calories to fuel their metabolisms that cold-blooded animals. However, despite this drawback, it pays off in the end because warm-blooded animals are able to acquire a lot more energy from their environment than their cold-blooded counterparts.
Hunting and gathering is a "high throughput" strategy which expends a lot more energy compared to the way other great apes go about getting their calories (which basically involves sitting around munching on nearby plants). It's possible that things like bipedalism and tool use made us energetically much more efficient at acquiring calories, and that's why we were able to engage in such an energy-intensive strategy. It's also possible that this strategy allows us to simply acquire a lot more calories from our surrounding environment than other apes. The question the researchers asked was which of these two explanations was correct.
The researchers ultimately concluded that it was the latter. Humans are not more efficient than other great apes at acquiring calories. Rather, humans' high-energy hunting and gathering methods allow us to get out hands on a lot more calories in a shorter amount of time. They also found that growing your own food (i.e. horticulture or subsistence farming) was another step up on that same ladder. Even though it's more work than foraging (although less than anticipated), it yields even more calories than hunting and gathering, meaning that it makes sense to do so from a purely energy budgeting standpoint.
Compared to chimpanzees, gorillas and orangutans, human hunter-gatherers are not particularly efficient at acquiring food...Walking in an upright/bipedal form makes humans move more efficiently than the other great apes, and we use sophisticated tools to make tasks easier to accomplish. However, humans (both hunter-gatherers and farmers) actually expend more energy per day on activities related to acquiring food than do chimpanzees, gorillas and orangutans. This makes our subsistence strategies not very efficient overall.
"It turns out we spend a surprising amount of energy getting food because we walk very long distances and engage in intense activities such as digging tubers or clearing trees...Other great apes, in contrast, don't need to go very far each day. Most of their food shopping involves leisurely picking fruit and vegetation."
However, humans do benefit from earning a lot more food energy per hour...humans' high-intensity subsistence activities yield many calories quickly..."...despite the intensity of the work, humans earn a much higher energetic 'salary' than do other apes... This ability to attain a higher return rate is what makes hunter-gatherers so successful." Add farming to the mix and that rate of return—or 'salary'—only increases.
Because we aren't that much more efficient than other great apes at getting our food, the necessity of procuring so many calories on a daily basis is a high-risk strategy that could easily backfire. However, humans have developed a number of unique strategies to overcome this problem, including the division of labor, sharing food with other people, and storing it up for potential shortfalls. As opposed to the the low-risk, low-reward strategy of other great apes, we have a high-risk, high-reward strategy, and we developed ways of mitigating some of those risks associated with that strategy to make it evolutionarily viable.
This ability to gather a lot of calories quickly also affords us a decent amount of free time which uniquely allows us to engage in the types of activities that allow for the development of complex culture—activities like gossip, storytelling, dancing, art, music, and so on.
...high throughput human strategies, which involve expending a lot of energy to get more food faster, can also be quite risky if you fail to get food on a given day. "Yet humans seem uniquely able to overcome this by cooperating and sharing and storing foods to avoid dangerous shortfalls."
Such cooperation has other benefits as well. Being able to meet one's daily food requirement in less time would have provided more opportunities for other endeavors. "Developing the rich social and cultural life so common in all human societies may first have required time-efficient strategies for feeding yourself..."
However, the downside of this strategy is that humans are hard-wired to get the maximum amount of calories for the minimum amount of effort. This worked well for us on the African savanna, but in a world of almost limitless abundance we are led astray. We can get all the food we need without hardly budging or lifting a finger. But this so-called 'laziness' is really just intelligent energy budgeting on a subconscious level.
"Part of what makes us humans so successful is being really good at figuring out how to get the biggest return for the least effort...You can see where that leads us today—driving cars or taking a bus to the local Costco to purchase those tasty $4.99 rotisserie chickens. We've replaced our physical labor in hunting or farming with supply chains. If we evolved to get calories cheaply, then the need to eat less or move more may be a struggle for good reason."
…On the other hand...the research findings suggest humans also evolved to be highly physically active, at least to attain food. "This doesn't mean we need to be vigorously active all the time...The lesson from subsistence populations is instead to just be less sedentary."
There were some other surprises from the study as well. It turns out that the amount of time subsistence farmers spend getting their food is actually not all that much greater than the amount of time hunter-gatherers do.
"We didn't expect that our cross-cultural database would reveal minimal difference in the amount of time spent working between hunter-gatherers and farming populations," ...As exemplified by James Suzman's recent book, "Work: A Deep History from the Stone Age to the Age of Robots," many anthropologists have long argued that hunter-gatherers spend very little time working as compared to other human societies. After compiling an exhaustive list of studies, the researchers found no evidence to support the idea that contemporary subsistence farmers spend more time working on average than hunter-gatherers.
From their conclusion (emphasis mine):
These findings revise our understanding of human energetics and evolution, indicating that humans afford expanded energy budgets primarily by increasing rates of energy acquisition, and not through energy-saving adaptations (such as economical bipedalism or sophisticated tool use) that decrease overall costs.
Relative to other great apes, human subsistence strategies are characterized by high-intensity, high-cost extractive activities and expanded day ranges that provide more calories in less time. These results suggest that energy gained from improvements in efficiency throughout human evolution were primarily channeled toward further increasing foraging intensity rather than reducing the energetic costs of subsistence. Greater energetic gains per unit time are the reward for humans’ intense and behaviorally sophisticated subsistence strategies.
Humans’ high-cost but high-return strategy is ecologically risky, and we argue that it was only possible in the context of increased cooperation, intergenerational food sharing, and a division of labor. We contend that the time saved by human subsistence strategies provided more leisure time for social interaction and social learning in central-place locations, which is critical for cumulative cultural evolution.
The second study is somewhat related to the first. Researchers looked at hominid hunting strategies over time going back several million years. As we saw above, humans are designed to go after the greatest amount of calories for the least amount of effort. Another way to say this is that we are evolved to seek out windfalls and exploit them1.
What the researchers found is that human hunters went after the largest animals in their surroundings, because they yielded the greatest number of calories. But by concentrating on the largest animals so intensely, those animals became much rarer, if not totally extinct. In response, humans went after the next largest animal. When that animal subsequently became scarce or extinct, they went after the next largest one, and so on.
The end result of this was that the the body mass of the animals we were hunting ten thousand years ago was only 1.7 percent the mass of the animals we were hunting 1.5 million years ago! The researches found that the body mass of animals declined log-linearly over time. Changes in climate and other factors did not account for this amount of decline—only human predation could explain it adequately.
As prey animals became smaller and smaller—and often more elusive and harder to capture—we altered our hunting technology accordingly. This drove "innovation" in tool use. Of course, smaller animals also yield less overall calories relative to the effort required to go after them (in other words, a decline in energy return on energy invested)
...at any given time early humans preferred to hunt the largest animals available in their surroundings, which provided the greatest quantities of food in return for a unit of effort.
In this way...early humans repeatedly overhunted large animals to extinction (or until they became so rare that they disappeared from the archaeological record) and then went on to the next in size, improving their hunting technologies to meet the new challenge.
The researchers also claim that about 10,000 years ago, when animals larger than deer became extinct, humans began to domesticate plants and animals to supply their needs, and this may be why the agricultural revolution began in the Levant at precisely that time…
"We may conclude that humans have always ravaged their environment but were usually clever enough to find solutions for the problems they had created."
TAU study tracks development of early humans’ hunting practices (Tel Aviv University)
Taken together, this makes the subsequent rise of farming (and everything that came after it) much easier to understand. One million years ago we were apex predators on top of the food chain. But we were too successful. Over time, the prey we went after gradually became smaller and smaller. We invented new technologies like the bow and arrow to cope with hunting smaller, more elusive, and more solitary prey. The prey we bagged yielded fewer and fewer calories. As a result, we incorporated more and more plant foods into our diet out of necessity. Our bodies shrank, as did our brains. In fact, the disappearance of elephants may have led to the expansion of our own, more generalist species in place of other hominid species who were more specialized in only hunting large prey:
Eventually we started intentionally growing plant foods in order to increase the amount of calories available to us even further. As we did so, food became more and more abundant, even if lower in overall nutritional quality. Cereal grains yielded the greatest amount calories for the least amount of effort—at least in the beginning. When the climate became more stable roughly ten thousand years ago, we doubled down putting more and more effort into growing our favored plant foods to support our growing populations, fundamentally altering our natural environment in the process. We developed new tools once again, changing over from the Paleolithic toolkit to the Neolithic one (the old stone age to the new stone age).
I have a book on my bookshelf called Too Smart for Our Own Good, which is a basically book-length elucidation of this trend (A Short History of Progress covers it as well). The author, Craig Dilworth, introduces what he calls the Vicious Circle Principle (VCP), which he defines as (emphasis in original):
Briefly put, [the VCP] says that in the case of humans the experience of need, resulting e.g. from changed environmental conditions, sometimes leads to technological innovation, which becomes widely employed, allowing more to be taken from the environment, thereby promoting population growth, which leads back to a situation of need.
Or, seeing it as a matter of a circle, it could for example be expressed as: increasing population size leads to technological innovation, which allows more to be taken from the environment, thereby promoting further population growth; or as: technological innovation allows more to be taken from the environment, the increase promoting population growth, which in turn creates a demand for further technological innovations. (p. 110)
Based on these studies, the VCP appears to have been kicked off by the disappearance of the large prey animals that we had co-evolved with to some extent. Everything—including many of our most fundamental innovations—has been a result of that.
I'm sure readers can extrapolate this to all sort of other things. There are far too may to go into in this post, but here are some of the most obvious:
Consider agriculture. Initially it dealt with the disappearance of large prey animals and produced large amounts of storable surpluses. Then population increased. Conflict intensified as people fought over those surpluses. Soil exhaustion and salinization, combined with periodic water shortages, led to bad harvests which led to famine which led to mass starvation on a much greater scale than ever before. So we came up with new and improved techniques to get more food from the land—from drawn plows to crop rotation to the cultivation of marginal lands to today's Green Revolution and GMO crops. Yet the quality of food and water is much worse overall than it was for our ancestors thousands of years ago.
Or consider the use of coal. Coal is much dirtier to burn than wood, and a lot harder to procure since it exists underground. But as timber became scarcer and had to be imported from farther and farther away, people started increasingly using it out of desperation. That increased need for coal led to the need to pump water out of the coal mines (it was originally called 'sea coal'), which led to the invention of the steam engine. The steam engine led to a greater use of coal, which only increased as engines became more and more efficient. This led to more crowding and more pollution. In turn, the need to solve those problems sparked another round of innovations (including sanitation and medicine). The ability to smelt iron using coal also led to a proliferation of iron and steel which was also necessary for the Industrial Revolution to take place.
Or consider fossil fuels. We started out using the highest-quality and most accessible sources. Now we're digging up brown lignite coal, splitting open shale rocks with toxic chemicals, and drilling a mile under the surface of the ocean to keep industrial society going—a society which we've deliberately engineered to require constant and never-ending growth. In each of these cases we exhausted the easiest to get resources first, and then went after harder and harder to get resources using technological innovations out of desperation.
Rather than innovation leading to a better life, the historical record clearly shows that innovations are designed primarily to solve immediate problems and typically lead to worse outcomes for the majority of people. The Industrial Revolution was the sole exception because we liberated several million years of ancient stored sunlight in the span of just a couple of centuries. But that will not last forever.
The only way to escape this vicious circle is to learn to live within limits. You would think Homo sapiens with our big brains could figure this out. Too bad that's never going to happen.
Fuel prices have pushed inflation to a thirty-year high, driving up the cost of a calorie of food. This is the second energy crisis. Apples are up by 25 per cent, margarine by 31 per cent, milk by 7 per cent. Food is more expensive and people have less to spend. Food bank users are turning down rice and pasta because of the cost of boiling a pan of water. Worse is to come. Ammonium nitrate fertiliser has risen from £280 to £1000 a tonne in the last year, reflecting the increased cost of the energy required to produce it. Crop yields will suffer, and food prices will continue to rise.
That phrasing comes from Charles Hugh Smith